Apparatus and circuit for processing carrier aggregation

ABSTRACT

A circuit for processing Carrier Aggregation (CA) is provided. The circuit includes a plurality of Component Carrier (CC) processors, each CC processor configured to estimate a frequency offset for a related CC and to compensate the estimated frequency offset, a reference clock generator configured to generate a reference clock using a reference frequency offset as one of frequency offsets output from the plurality of CC processors, a plurality of reception Phase Lock Loop (PLL) units, each reception PLL unit configured to generate a reception carrier frequency for the related CC corresponding to the reference clock, and a plurality of transmission PLL units, each transmission PLL unit configured to generate a transmission carrier frequency for the related CC corresponding to the reference clock.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 14/152,297, filed on Jan. 10, 2014, which claimed the benefit under35 U.S.C. §119(a) of a Korean patent application filed on Mar. 20, 2013in the Korean Intellectual Property Office and assigned Serial No.10-2013-0029965, the entire disclosure of each of which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and circuit forprocessing Carrier Aggregation (CA) in a wireless communication system.More particularly, the present disclosure relates to an apparatus andcircuit for processing CA using a Component Carrier (CC) in a wirelesscommunication system.

BACKGROUND

In a Long Term Evolution-Advanced (LTE-A) mobile communication system ofthe related art, a CA scheme has been used. The CA scheme is a scheme inwhich a CC is added in order to increase a data rate without impactinguse of a legacy User Equipment (UE), which uses a single carrier. The CAscheme has been applied in the Release 10 version in the LTE mobilecommunication system, and, for example, the maximum number of CCs usedin the CA scheme is five.

However, there is not currently a design for a MOdulator/DE-Modulator(MODEM) that considers the CA scheme.

The CA scheme is divided into an intra-band CA scheme, in which CCs arein the same frequency band, and an inter-band CA scheme, in which theCCs are in different frequency bands according to carrier frequencyallocation for each CC. The inter-band CA scheme may be specified into acontiguous CA scheme, in which CCs are in contiguous frequency bands,and a non-contiguous CA scheme, in which the CCs are in non-contiguousfrequency bands according to frequency separation among CCs.

Based on frequency usage fairness, network providers are allocated a CCby 5˜10 MHz in the same frequency band. Therefore, the CA scheme isgenerally implemented with a non-contiguous CA scheme or an inter-bandCA scheme rather than an intra-band contiguous CA scheme.

In multi-carrier schemes of the related art, a receiver performs afrequency down conversion operation and a filtering operation based on acenter frequency of more than two contiguous bandwidths which have arelatively narrow system bandwidth and performs a filtering operationper frequency bandwidth in an analog domain or a digital domain in orderto receive more than two contiguous bandwidths which have the relativelynarrow system bandwidth. For example, in the LTE mobile communicationsystem, it should be assumed that a signal of each of contiguousbandwidths is received in the same Node B at the same timing.

However, a CA scheme which is currently considered in the LTE mobilecommunication system is operated based on signals which are transmittedat different timing points from two Node Bs which are at differentlocations and have different frequency offsets.

In CA schemes of the related art, multiple channels with contiguous CCsare processed such that it is impossible to properly compensate afrequency offset if a timing point of a signal is changed or a frequencyoffset is changed. This causes a decrease of transmission/receptionperformance. Thus, the CA schemes of the related art may not be used ifa signal is transmitted/received through an inter-band or an intra-bandnon-contiguous bandwidth.

Accordingly, a need exists for an improved apparatus and method forprocessing CA.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide an apparatus and circuit for processing CarrierAggregation (CA).

Another aspect of the present disclosure is to provide an apparatus andcircuit for processing CA using a reference Component Carrier (CC).

Another aspect of the present disclosure is to provide apparatus andcircuit for processing CA using one reference clock.

Another aspect of the present disclosure is to provide an apparatus andcircuit for processing CA by considering a deployment scenario forvarious CCs.

In accordance with an aspect of the present disclosure, a circuit forprocessing CA is provided. The circuit includes a plurality of CCprocessors, each CC processor configured to estimate a frequency offsetfor a related CC and to compensate the estimated frequency offset, areference clock generator configured to generate a reference clock usinga reference frequency offset as one of frequency offsets output from theplurality of CC processors, a plurality of reception Phase Lock Loop(PLL) units, each reception PLL unit configured to generate a receptioncarrier frequency for the related CC corresponding to the referenceclock, and a plurality of transmission PLL units, each transmission PLLunit configured to generate a transmission carrier frequency for therelated CC corresponding to the reference clock.

In accordance with another aspect of the present disclosure, anapparatus for processing CA is provided. The apparatus includes aplurality of CC processors, each CC processor configured to estimate afrequency offset for a related CC and to compensate the estimatedfrequency offset, a reference clock generator configured to generate areference clock using a reference frequency offset as one of frequencyoffsets output from the plurality of CC processors, a plurality ofreception PLL units, each reception PLL unit configured to generate areception carrier frequency for the related CC corresponding to thereference clock, and a plurality of transmission PLL units, eachtransmission PLL unit configured to generate a transmission carrierfrequency for the related CC corresponding to the reference clock.

In accordance with another aspect of the present disclosure, a circuitfor processing CA is provided. The circuit includes a plurality of CCprocessors, each CC processor configured to estimate a frequency offsetfor a related CC, a reference clock generator configured to generate areference clock using a reference frequency offset as one of frequencyoffsets output from the plurality of CC processors, a plurality ofreception PLL units, each reception PLL unit configured to generate areception carrier frequency for the related CC corresponding to thereference clock and to compensate the estimated frequency offset, and aplurality of transmission PLL units, each transmission PLL unitconfigured to generate a transmission carrier frequency for the relatedCC corresponding to the reference clock and to compensate the estimatedfrequency offset.

In accordance with another aspect of the present disclosure, anapparatus for processing CA is provided. The apparatus includes aplurality of CC processors, each CC processor configured to estimate afrequency offset for a related CC, a reference clock generatorconfigured to generate a reference clock using a reference frequencyoffset as one of frequency offsets output from the plurality of CCprocessors, a plurality of reception PLL units, each reception PLL unitconfigured to generate a reception carrier frequency for the related CCcorresponding to the reference clock and to compensate the estimatedfrequency offset, and a plurality of transmission PLL units, eachtransmission PLL unit configured to generate a transmission carrierfrequency for the related CC corresponding to the reference clock and tocompensate the estimated frequency offset.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A schematically illustrates an internal structure of a CarrierAggregation (CA) processing apparatus in a wireless communication systemaccording to an embodiment of the present disclosure;

FIG. 1B schematically illustrates an internal structure of a ComponentCarrier (CC) processor, such as the CC processor #1 110 in FIG. 1A,according to an embodiment of the present disclosure;

FIG. 1C schematically illustrates an internal structure of a CCprocessor, such as the CC processor #1 120 in FIG. 1A, according to anembodiment of the present disclosure;

FIG. 1D schematically illustrates an internal structure of a CCprocessor, such as the CC processor # N 130 in FIG. 1A, according to anembodiment of the present disclosure;

FIG. 2A schematically illustrates an internal structure of a CAprocessing apparatus in a wireless communication system according to anembodiment of the present disclosure;

FIG. 2B schematically illustrates an internal structure of a CCprocessor, such as the CC processor #0 210 in FIG. 2A, according to anembodiment of the present disclosure;

FIG. 2C schematically illustrates an internal structure of a CCprocessor, such as the CC processor #1 220 in FIG. 2A, according to anembodiment of the present disclosure; and

FIG. 2D schematically illustrates an internal structure of a CCprocessor, such as the CC processor # N 230 in FIG. 2A, according to anembodiment of the present disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Although ordinal numbers such as “first”, “second”, and so forth will beused to describe various components, those components are not limited bythe terms. The terms are used only for distinguishing one component fromanother component. For example, a first component may be referred to asa second component and likewise, a second component may also be referredto as a first component, without departing from the teaching of theinventive concept. The term “and/or” used herein includes any and allcombinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing embodimentsonly and is not intended to be limiting of the embodiments. As usedherein, the singular forms are intended to include the plural forms aswell, unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises” and/or “has” when used in thisspecification, specify the presence of a stated feature, number, step,operation, component, element, or a combination thereof but do notpreclude the presence or addition of one or more other features,numbers, steps, operations, components, elements, or combinationsthereof.

The terms used herein, including technical and scientific terms, havethe same meanings as terms that are generally understood by thoseskilled in the art, as long as the terms are not differently defined. Itshould be understood that terms defined in a generally-used dictionaryhave meanings coinciding with those of terms in the related technology.As long as the terms are not defined obviously, they are not ideally orexcessively analyzed as formal meanings.

An embodiment of the present disclosure proposes an apparatus andcircuit for processing Carrier Aggregation (CA).

An embodiment of the present disclosure proposes an apparatus andcircuit for processing CA using a reference Component Carrier (CC).

An embodiment of the present disclosure proposes an apparatus andcircuit for processing CA using one reference clock.

An embodiment of the present disclosure proposes an apparatus andcircuit for processing CA by considering a deployment scenario forvarious CCs.

An apparatus and method proposed in an embodiment of the presentdisclosure may be applied to various mobile communication systems suchas a Long Term Evolution (LTE) mobile communication system, a Long TermEvolution-Advanced (LTE-A) mobile communication system, a High SpeedDownlink Packet Access (HSDPA) mobile communication system, a High SpeedUplink Packet Access (HSUPA) mobile communication system, a High RatePacket Data (HRPD) mobile communication system proposed in a 3 ^(rd)Generation Project Partnership 2 (3GPP2), a Wideband Code DivisionMultiple Access (WCDMA) mobile communication system proposed in a 3GPP2,a Code Division Multiple Access (CDMA) mobile communication systemproposed in a 3GPP2, an Institute of Electrical and ElectronicsEngineers (IEEE) mobile communication system, an Evolved Packet System(EPS), and the like.

FIG. 1A schematically illustrates an internal structure of a CAprocessing apparatus in a wireless communication system according to anembodiment of the present disclosure;

FIG. 1B schematically illustrates an internal structure of a CCprocessor, such as the CC processor #0 110 in FIG. 1A, according to anembodiment of the present disclosure;

FIG. 1C schematically illustrates an internal structure of a CCprocessor, such as the CC processor #1 120 in FIG. 1A, according to anembodiment of the present disclosure; and

FIG. 1D schematically illustrates an internal structure of a CCprocessor, such as the CC processor # N 130 in FIG. 1A, according to anembodiment of the present disclosure.

Prior to a description of FIGS. 1A to 1D, it will be noted that aninternal structure of a CA processing apparatus in FIGS. 1A to 1D is aninternal structure of a CA processing apparatus based on a frequencycompensator.

Referring to FIG. 1A, the CA processing apparatus includes a pluralityof reception antennas, e.g., M reception antennas, i.e., a receptionantenna ANT #1 to a reception antenna ANT #M, a plurality of CCprocessors, e.g., N+1 CC processors, i.e., a CC processor #0110, a CCprocessor #1 120, . . . , a CC processor # N 130, a controller 140, areference clock generator 150, a plurality of reception Phase Lock Loop(PLL) units, e.g., N+1 reception PLL units, i.e., a reception PLL unit#0 160-0, a reception PLL unit #1 160-1, . . . , a reception PLL unit #N160-N, and a plurality of transmission PLL units, e.g., N+1 transmissionPLL units, i.e., a transmission PLL unit #0 170-0, a transmission PLLunit #1 170-1, . . . , a transmission PLL unit #N 170-N.

Referring to FIG. 1B, the CC processor #0 110 includes M FrequencyDown-Converters (FDCs), i.e., an FDC #1 111-1, . . . , an FDC # M 111-Mwhich are coupled to M reception antennas, i.e., a reception antennaANT#1 to a reception antenna ANT#M, respectively, M FrequencyUp-Converters (FUCs), i.e., an FUC #1 113-1, . . . , an FUC # M 113-Mwhich are coupled to the reception antenna ANT#1 to the receptionantenna ANT#M, respectively, M Reception Frequency Offset Compensators(RFOCs), i.e., an RFOC #1 115-1, . . . , an RFOC #M 115-M which arecoupled to the M FDCs, respectively, M Transmission Frequency OffsetCompensators (TFOCs), i.e., a TFOC #1 117-1, . . . , a TFOC #M 117-Mwhich are coupled to the M FUCs, respectively, and a frequency offsetestimator 119.

Referring to FIG. 1C, the CC processor #1 120 includes M FDCs, i.e., anFDC #1 121-1, . . . , an FDC # M 121-M which are coupled to thereception antenna ANT#1 to the reception antenna ANT#M, respectively, MFUCs, i.e., an FUC #1 123-1, . . . , an FUC # M 123-M which are coupledto the reception antenna ANT#1 to the reception antenna ANT#M,respectively, M RFOCs, i.e., an RFOC #1 125-1, . . . , an RFOC #M 125-Mwhich are coupled to the M FDCs, respectively, M TFOCs, i.e., a TFOC #1127-1, . . . , a TFOC #M 127-M which are coupled to the M FUCs,respectively, and a frequency offset estimator 129.

Referring to FIG. 1D, the CC processor # N 130, as the last CCprocessor, includes M FDCs, i.e., an FDC #1 131-1, . . . , an FDC # M131-M which are coupled to the reception antenna ANT#1 to the receptionantenna ANT#M, respectively, M FUCs, i.e., an FUC #1 133-1, . . . , anFUC # M 133-M which are coupled to the reception antenna ANT#1 to thereception antenna ANT#M, respectively, M RFOCs, i.e., an RFOC #1 135-1,. . . , an RFOC #M 135-M which are coupled to the M FDCs, respectively,M TFOCs, i.e., a TFOC #1 137-1, . . . , a TFOC #M 137-M which arecoupled to the M FUCs, respectively, and a frequency offset estimator139.

As illustrated in FIGS. 1A to 1D, the CA processing apparatus includesonly one reference clock generator, i.e., the reference clock generator150, and the reference clock generator 150 generates a reference clock.For example, the reference clock generator 150 may be implemented as aTemperature Compensated Crystal Oscillator (TCXO) or a DigitallyCompensated Crystal Oscillator (DCXO). In FIGS. 1A to 1D, while thereference clock generator 150 is implemented as a TCXO or a DCXO, thereference clock generator 150 may be implemented with various forms.

Each of the reception PLL units, i.e., the reception PLL unit #0 160-0,the reception PLL unit #1 160-1, . . . , the reception PLL unit #N160-N, is connected to the reference clock generator 150, and generatesa Reception Carrier Frequency (RCF) for each CC using the referenceclock which is generated in the reference clock generator 150. Thereception PLL unit #0 160-0 generates an RCF for a CC #0, and thereception PLL unit #1 160-1 generates an RCF for a CC #1. In this way,the reception PLL unit #N 160-N, as the last reception PLL unit,generates an RCF for a CC #N.

Each of the transmission PLL units, i.e., the transmission PLL unit #0170-0, the transmission PLL unit #1 170-1, . . . , the transmission PLLunit #N 170-N, is connected to the reference clock generator 150, andgenerates a Transmission Carrier Frequency (TCF) for each CC using thereference clock which is generated in the reference clock generator 150.The transmission PLL unit #0 170-0 generates a TCF for the CC #0, andthe transmission PLL unit #1 170-1 generates a TCF for the CC #1. Inthis way, the transmission PLL unit #N 170-N, as the last transmissionPLL unit, generates a TCF for the CC #N.

The CA processing apparatus includes one reference clock generator 150,and includes PLL units which may generate a TCF and an RCF for each CCbased on the one reference clock generator 150 for each transmissionpath and each reception path.

If it is assumed that a Reference Reception Carrier Frequency Signal(RRCFS) for a CC#n (n=0, 1, 2, . . . , N) is “Rx_fn” and a ReferenceTransmission Carrier Frequency Signal for the CC#n is “Tx_fn”, the Rx_fnis provided to an FDC for receiving a carrier frequency signal for eachCC#n and the Tx_fn is provided to an FUC for transmitting the carrierfrequency signal.

For example, an RRCFS for the CC #0 is “Rx_f0”, an RTCFS for the CC #0is “Tx_f0”, the Rx_f0 is provided to the FDC #1 111-1 to the FDC #M111-M for receiving a carrier frequency signal of the CC #0, and theTx_f0 is provided to the FUC #1 113-1 to the FUC #M 113-M fortransmitting the carrier frequency signal of the CC #0. Further, anRRCFS for the CC #1 is “Rx_f1”, an RTCFS for the CC #1 is “Tx_f1”, theRx_f1 is provided to the FDC #1 121-1 to the FDC #M 121-M for receivinga carrier frequency signal of the CC #1, and the Tx_f1 is provided tothe FUC #1 123-1 to the FUC #M 123-M for transmitting the carrierfrequency signal of the CC #1. In this way, an RRCFS for the CC #N, asthe last CC, is “Rx_fN”, an RTCFS for the CC #N is “Tx_fN”, the Rx_fN isprovided to the FDC #1 131-1 to the FDC #M 131-M for receiving a carrierfrequency signal of the CC #N, and the Tx_fN is provided to the FUC #1133-1 to the FUC #M 133-M for transmitting the carrier frequency signalof the CC #N.

A frequency offset estimator included in each CC processor is connectedto M RFOCs included in a related CC processor, and estimates a frequencyoffset CC#n_Fo as a difference between an RRCFS which is provided toeach CC processor through the N+1 reception PLL units included in the CAprocessing apparatus, i.e., the reception PLL unit #0 160-0, thereception PLL unit #1 160-1, . . . , the reception PLL unit #N 160-N anda received carrier frequency signal.

The frequency offset estimator 119 included in the CC processor #0 110is connected to the RFOC #1 115-1, . . . , the RFOC #M 115-M, andestimates a CC#0_Fo as a frequency offset which is a difference betweenan RRCFS Rx_f0 which is provided through the reception PLL unit #0160-0, the reception PLL unit #1 160-1, . . . , the reception PLL unit #N 160-N, and the received carrier frequency signal.

The frequency offset estimator 129 included in the CC processor #1 120is connected to the RFOC #1 125-1, . . . , the RFOC #M 125-M, andestimates a CC#1_Fo as a frequency offset which is a difference betweenan RRCFS Rx_f1 which is provided through the reception PLL unit #0160-0, the reception PLL unit #1 160-1, . . . , the reception PLL unit #N 160-N, and the received carrier frequency signal.

In this way, the frequency offset estimator 129, as the last frequencyoffset estimator included in the CC processor #N 130, is connected tothe RFOC #1 135-1, . . . , the RFOC #M 135-M, and estimates a CC#N_Fo asa frequency offset which is a difference between an RRCFS Rx_fN which isprovided through the reception PLL unit #0 160-0, the reception PLL unit#1 160-1, . . . , the reception PLL unit # N 160-N, and the receivedcarrier frequency signal.

Each CC processor compensates a transmission frequency offset and areception frequency offset, a description of which will be providedbelow.

Firstly, an operation of compensating the reception frequency offset ineach CC processor will be described.

An RFOC included in each CC processor compensates a reception frequencyoffset using the frequency offset CC#n_Fo output from a frequency offsetestimator included in a related CC processor.

For example, in the CC processor #0 110, the RFOC #1 115-1 is connectedto the FDC #1 111-1, and estimates the reception frequency offset usingthe CC#0_Fo as the frequency offset output from the frequency offsetestimator 119. In this way, the RFOC #M 115-M, as the last RFOC, isconnected to the FDC #M 111-M, and estimates the reception frequencyoffset using the CC#0_Fo.

In the CC processor #1 120, the RFOC #1 125-1 is connected to the FDC #1121-1, and estimates the reception frequency offset using the CC#1_Fo asthe frequency offset output from the frequency offset estimator 129. Inthis way, the RFOC #M 125-M, as the last RFOC, is connected to the FDC#M 121-M, and estimates the reception frequency offset using theCC#1_Fo.

In the CC processor # N 130, as the last CC processor, the RFOC #1 135-1is connected to the FDC #1 131-1, and estimates the reception frequencyoffset using the CC#N_Fo as the frequency offset output from thefrequency offset estimator 139. In this way, the RFOC #M 135-M, as thelast RFOC, is connected to the FDC #M 131-M, and estimates the receptionfrequency offset using the CC#N_Fo.

Secondly, an operation of compensating the transmission frequency offsetin each CC processor will be described.

A TFOC included in each CC processor compensates a transmissionfrequency offset using the frequency offset CC#n_Fo output from thefrequency offset estimator included in a related CC processor.

For example, in the CC processor #0 110, the TFOC #1 117-1 is connectedto the FUC #1 113-1, and estimates the transmission frequency offsetusing the CC#0_Fo as the frequency offset output from the frequencyoffset estimator 119. In this way, the TFOC #M 117-M, as the last TFOC,is connected to the FUC #M 113-M, and estimates the transmissionfrequency offset using the CC#0_Fo.

In the CC processor #1 120, the TFOC #1 127-1 is connected to the FUC #1123-1, and estimates the transmission frequency offset using the CC#1_Foas the frequency offset output from the frequency offset estimator 129.In this way, the TFOC #M 127-M, as the last TFOC, is connected to theFUC #M 123-M, and estimates the transmission frequency offset using theCC#1_Fo.

In the CC processor # N 130, as the last CC processor, the TFOC #1 137-1is connected to the FUC #1 133-1, and estimates the transmissionfrequency offset using the CC#N_Fo as the frequency offset output fromthe frequency offset estimator 139. In this way, the TFOC #M 137-M, asthe last TFOC, is connected to the FUC #M 133-M, and estimates thetransmission frequency offset using the CC#N_Fo.

For example, each of the TFOCs and the RFOCs in each CC processor may beimplemented as a phase rotator such as a COordinate Rotation DIgitalComputer (CORDIC), or a Read Only Table (ROM) table, or a module whichmay convert a frequency of a signal such as a complex multiplierbased-phase converter. In an embodiment of the present disclosure, theTFOCs and the RFOCs are implemented as phase rotators, ROM tables, orphase converters. However, it will be understood by those of ordinaryskill in the art that the TFOCs and the RFOCs may be implemented withvarious forms.

An operation of a CA processing apparatus according to an embodiment ofthe present disclosure will be described with reference to FIGS. 1A to1D.

A reference clock for the CA processing apparatus compensates afrequency offset based on a frequency offset which is estimated in afrequency offset estimator included in a related CC processorcorresponding to a CC which is selected from among N+1 CCs, i.e., theCC#0 to the CC#N, i.e., a reference frequency offset. In this case, afrequency offset compensator included in a transmission path and areception path is not operated for the selected CC.

The CA processing apparatus may perform a reference clock controloperation based on a CC which has the best channel quality among the N+1CCs, i.e., the CC#0 to the CC#N. Here, the channel quality may bedetermined using various metrics such as a Carrier-to-Interference andNoise Ratio (CINR), Reference Signal Received Power (RSRP), a ReferenceSignal Received Quality (RSRQ), a Reference Signal Strength Indicator(RSSI), a Channel Quality Indicator (CQI), and a BLock Error Rate (BLER)for a control channel or a data channel for each CC. In FIGS. 1A to 1D,the various metrics such as the CINR, the RSRP, the RSRQ, the RSSI, theCQI, and the BLER are used for selecting a CC used for the referenceclock control operation. However, it will be understood by those ofordinary skill in the art that metrics used for selecting the CC usedfor the reference clock control operation are not limited.

The CA processing apparatus may perform a reference clock controloperation based on a CC having the best channel quality among N+1 CCs,i.e., the CC#0 to the CC#N. For example, a period of selecting a CC usedfor the reference clock control operation may be a measurement period bywhich various metrics such as the CINR, the RSRP, the RSRQ, the RSSI,the CQI, and the BLER are measured. If the various metrics such as theCINR, the RSRP, the RSRQ, the RSSI, the CQI, and the BLER are filtered,the period of selecting the CC used for the reference clock controloperation may be set to a multiple of the measurement period.

A frequency offset which is estimated in a frequency offset estimatorincluded in CC processors corresponding to remaining CCs which are notused for controlling the reference clock is used for compensating afrequency offset through TFOCs and RFOCs included in a related CCprocessor.

FIG. 2A schematically illustrates an internal structure of a CAprocessing apparatus in a wireless communication system according to anembodiment of the present disclosure;

FIG. 2B schematically illustrates an internal structure of a CCprocessor, such as the CC processor #0 210 in FIG. 2A, according to anembodiment of the present disclosure;

FIG. 2C schematically illustrates an internal structure of a CCprocessor, such as the CC processor #1 220 in FIG. 2A, according to anembodiment of the present disclosure; and

FIG. 2D schematically illustrates an internal structure of a CCprocessor, such as the CC processor # N 230 in FIG. 2A, according to anembodiment of the present disclosure.

Prior to a description of FIGS. 2A to 2D, it will be noted that aninternal structure of a CA processing apparatus in FIGS. 2A to 2D is aninternal structure of a CA processing apparatus based on PLL control.

Referring to FIG. 2A, the CA processing apparatus includes a pluralityof reception antennas, e.g., M reception antennas, i.e., a receptionantenna ANT #1 to a reception antenna ANT #M, a plurality of CCprocessors, e.g., N+1 CC processors, i.e., a CC processor #0 210, a CCprocessor #1 220, . . . , a CC processor # N 230, a controller 240, areference clock generator 250, a plurality of reception PLL units, e.g.,N+1 reception PLL units, i.e., a reception PLL unit #0 260-0, areception PLL unit #1 260-1, . . . , a reception PLL unit #N 260-N, anda plurality of transmission PLL units, e.g., N+1 transmission PLL units,i.e., a transmission PLL unit #0 270-0, a transmission PLL unit #1270-1, . . . , a transmission PLL unit #N 270-N.

Referring to FIG. 2B, the CC processor #0 210 includes M FDCs, i.e., anFDC #1 211-1, . . . , an FDC # M 211-M which are coupled to M receptionantennas, i.e., a reception antenna ANT#1 to a reception antenna ANT#M,respectively, M FUCs, i.e., an FUC #1 213-1, . . . , an FUC # M 213-Mwhich are coupled to the reception antenna ANT#1 to the receptionantenna ANT#M, respectively, and a frequency offset estimator 215 whichis connected to each of the M FDCs.

Referring to FIG. 2C, the CC processor #1 220 includes M FDCs, i.e., anFDC #1 221-1, . . . , an FDC# M 221-M which are coupled to the receptionantenna ANT#1 to the reception antenna ANT#M, respectively, M FUCs,i.e., an FUC #1 223-1, . . . , an FUC # M 223-M which are coupled to thereception antenna ANT#1 to the reception antenna ANT#M, respectively,and a frequency offset estimator 225 which is connected to each of the MFDCs.

Referring to FIG. 2D, the CC processor # N 230, as the last CCprocessor, includes M FDCs, i.e., an FDC #1 231-1, . . . , an FDC # M231-M which are coupled to the reception antenna ANT#1 to the receptionantenna ANT#M, respectively, M FUCs, i.e., an FUC #1 233-1, . . . , anFUC # M 233-M which are coupled to the reception antenna ANT#1 to thereception antenna ANT#M, respectively, and a frequency offset estimator235 which is connected to each of the M FDCs.

As illustrated in FIGS. 2A to 2D, the CA processing apparatus includesone reference clock generator, i.e., the reference clock generator 250,and the reference clock generator 250 generates a reference clock. Forexample, the reference clock generator 250 may be implemented as a TCXOor a DCXO. In FIGS. 2A to 2D, while the reference clock generator 250 isimplemented as a TCXO or a DCXO, the reference clock generator 250 maybe implemented with various forms.

Each of the reception PLL units, i.e., the reception PLL unit #0 260-0,the reception PLL unit #1 260-1, . . . , the reception PLL unit #N260-N, is connected to the reference clock generator 250, and generatesa reception carrier frequency for each CC using the reference clockwhich is generated in the reference clock generator 250. The receptionPLL unit #0 260-0 generates a reception carrier frequency for a CC #0,and the reception PLL unit #1 260-1 generates a reception carrierfrequency for a CC #1. In this way, the reception PLL unit #N 260-N, asthe last reception PLL unit, generates a reception carrier frequency fora CC #N.

Each of the transmission PLL units, i.e., the transmission PLL unit #0270-0, the transmission PLL unit #1 270-1, . . . , the transmission PLLunit #N 270-N, is connected to the reference clock generator 250, andgenerates a transmission carrier frequency for each CC using thereference clock which is generated in the reference clock generator 250.The transmission PLL unit #0 270-0 generates a transmission carrierfrequency for the CC #0, and the transmission PLL unit #1 270-1generates a transmission carrier frequency for the CC #1. In this way,the transmission PLL unit #N 270-N, as the last transmission PLL unit,generates a transmission carrier frequency for the CC #N.

The CA processing apparatus includes one reference clock generator 250,and includes PLL units which may generate a TCF and an RCF for each CCbased on the one reference clock generator for each transmission pathand each reception path.

If it is assumed that an RRCFS for a CC#n (n=0, 1, 2, . . . , N) is“Rx_fn” and an RTCFS for the CC#n is “Tx_fn”, the Rx_fn is provided toan FDC for receiving a carrier frequency signal for each CC#n and theTx_fn is provided to an FUC for transmitting the carrier frequencysignal.

For example, an RRCFS for the CC #0 is “Rx_f0”, an RTCFS for the CC #0is “Tx_f0”, the Rx_f0 is provided to the FDC #1 211-1 to the FDC #M211-M for receiving a carrier frequency signal of the CC #0, and theTx_f0 is provided to the FUC #1 213-1 to the FUC #M 213-M fortransmitting the carrier frequency signal of the CC #0. Further, anRRCFS for the CC #1 is “Rx_f1”, an RTCFS for the CC #1 is “Tx_f1”, theRx_f1 is provided to the FDC #1 221-1 to the FDC #M 221-M for receivinga carrier frequency signal of the CC #1, and the Tx_f1 is provided tothe FUC #1 223-1 to the FUC #M 223-M for transmitting the carrierfrequency signal of the CC #1. In this way, an RRCFS for the CC #N, asthe last CC, is “Rx_fN”, an RTCFS for the CC #N is “Tx_fN”, the Rx_fN isprovided to the FDC #1 231-1 to the FDC #M 231-M for receiving a carrierfrequency signal of the CC #N, and the Tx_fN is provided to the FUC #1233-1 to the FUC #M 233-M for transmitting the carrier frequency signalof the CC #N.

A frequency offset estimator included in each CC processor is connectedto M RFOCs included in a related CC processor, and estimates a frequencyoffset CC#n_Fo as a difference between an RRCFS, which is provided toeach CC processor through the N+1 reception PLL units included in the CAprocessing apparatus, i.e., the reception PLL unit #0 260-0, thereception PLL unit #1 260-1, . . . , the reception PLL unit #N 260-Nnand a received carrier frequency signal.

The frequency offset estimator 215 included in the CC processor #0 210is connected to the FDC #1 211-1, . . . , the FDC #M 211-M, andestimates a CC#0_Fo as a frequency offset which is a difference betweenan RRCFS Rx_f0 which is provided through the reception PLL unit #0260-0, the reception PLL unit #1 260-1, . . . , the reception PLL unit #N 260-N, and the received carrier frequency signal.

The frequency offset estimator 225 included in the CC processor #1 220is connected to the FDC #1 221-1, . . . , the FDC #M 221-M, andestimates a CC#1_Fo as a frequency offset which is a difference betweenan RRCFS Rx_f1 which is provided through the reception PLL unit #0260-0, the reception PLL unit #1 260-1, . . . , the reception PLL unit #N 260-N, and the received carrier frequency signal.

In this way, the frequency offset estimator 235, as the last frequencyoffset estimator included in the CC processor #N 230, is connected tothe FDC #1 231-1, . . . , the FDC #M 231-M, and estimates a CC#N_Fo as afrequency offset which is a difference between an RRCFS Rx_fN which isprovided through the reception PLL unit #0 260-0, the reception PLL unit#1 260-1, . . . , the reception PLL unit # N 260-N, and the receivedcarrier frequency signal.

The CA processing apparatus in FIGS. 2A to 2D compensates a frequencyoffset estimated in each CC by controlling a reception PLL unit and atransmission PLL unit for a related CC, a description of which will beprovided followed.

Firstly, a scheme in which the CA processing apparatus compensates thefrequency offset estimated in each CC by controlling the reception PLLunit for the related CC will be described.

The frequency offset CC#0_Fo for the CC#0 is inputted to the receptionPLL unit #0 260-0, thereby the reception PLL unit #0 260-0 compensatesthe estimated frequency offset CC#0_Fo.

The frequency offset CC#1_Fo for the CC#1 is inputted to the receptionPLL unit #1 260-1, thereby the reception PLL unit #1 260-1 compensatesthe estimated frequency offset CC#1_Fo.

The frequency offset CC#N_Fo for the CC#N is inputted to the receptionPLL unit #N 260-N, thereby the reception PLL unit #N 260-N compensatesthe estimated frequency offset CC#N_Fo.

Secondly, a scheme in which the CA processing apparatus compensates thefrequency offset estimated in each CC by controlling the transmissionPLL unit for the related CC will be described.

The frequency offset CC#0_Fo for the CC#0 is inputted to thetransmission PLL unit #0 270-0, thereby the transmission PLL unit #0270-0 compensates the estimated frequency offset CC#0_Fo.

The frequency offset CC#1_Fo for the CC#1 is inputted to thetransmission PLL unit #1 270-1, thereby the transmission PLL unit #1270-1 compensates the estimated frequency offset CC#1_Fo.

The frequency offset CC#N_Fo for the CC#N is inputted to thetransmission PLL unit #N 270-N, thereby the transmission PLL unit #N270-N compensates the estimated frequency offset CC#N_Fo.

An operation of a CA processing apparatus according to an embodiment ofthe present disclosure will be described with reference to FIGS. 2A to2D.

A reference clock for the CA processing apparatus compensates afrequency offset based on a frequency offset which is estimated in afrequency offset estimator included in a related CC processorcorresponding to a CC which is selected from among N+1 CCs, i.e., theCC#0 to the CC#N, i.e., a reference frequency offset.

The CA processing apparatus may perform a reference clock controloperation based on a CC which has the best channel quality among the N+1CCs, i.e., the CC#0 to the CC#N. Here, the channel quality may bedetermined using various metrics such as a CINR, an RSRP, an RSRQ, anRSSI, a CQI, and a BLER for a control channel or a data channel for eachCC. In FIGS. 2A to 2D, the various metrics such as the CINR, the RSRP,the RSRQ, the RSSI, the CQI, and the BLER are used for selecting a CCused for the reference clock control operation. However, it will beunderstood by those of ordinary skill in the art that metrics used forselecting the CC used for the reference clock control operation are notlimited.

The CA processing apparatus may perform a reference clock controloperation based on a CC having the best channel quality among N+1 CCs,i.e., the CC#0 to the CC#N. For example, a period of selecting a CC usedfor the reference clock control operation may be a measurement period bywhich various metrics such as the CINR, the RSRP, the RSRQ, the RSSI,the CQI, and the BLER are measured. If the various metrics such as theCINR, the RSRP, the RSRQ, the RSSI, the CQI, and the BLER are filtered,the period of selecting the CC used for the reference clock controloperation may be set to a multiple of the measurement period.

Meanwhile, a frequency offset which is estimated in a frequency offsetestimator included in CC processors corresponding to remaining CCs whichare not used for controlling the reference clock is used for controllinga related transmission/reception PLL unit and compensating a frequencyoffset.

The frequency offset which is estimated in the frequency offsetestimator included in the CC processors corresponding to the remainingCCs which are not used for controlling the reference clock is used forcompensating the frequency offset through TFOCs and RFOCs included in arelated CC processor.

In FIGS. 2A to 2D, a CA processing apparatus compensates a frequency bycompensating a frequency offset for a transmission PLL unit and areception PLL unit in each CC without using a separated frequency offsetcompensator, so there is a need for providing a control signal from aMOdulator/DE-Modulator (MODEM) to a Radio Frequency Integrated Circuit(RFIC) by a frequency offset compensation period.

A CC processing circuit and/or a CC processing apparatus according toembodiments of the present disclosure as described in FIGS. 1A to 2Dprocesses a CA with reference to a case in which the number ofprocessors for receiving a signal is equal to the number of processorsfor transmitting a signal. However, it will be understood by those ofordinary skill in the art that the number of processors for receivingthe signal may be equal to or different from the number of processorsfor transmitting the signal.

Further, it will be understood by those of ordinary skill in the artthat the number of antennas and the number of CCs in a CC processingcircuit and/or a CC processing apparatus according to embodiments of thepresent disclosure as described in FIGS. 1A to 2D are not limited.

As is apparent from the foregoing description, an embodiment of thepresent disclosure enables processing CA using a reference CC.

An embodiment of the present disclosure enables processing CA using onereference clock.

An embodiment of the present disclosure enables processing CA byconsidering a deployment scenario for various CCs.

An embodiment of the present disclosure enables processing CA withoutusing a reference clock for each CC thereby minimizing a cost and asize.

An embodiment of the present disclosure enables compensation of afrequency offset per CC thereby providing various deployment scenariosand flexibly processing CA. So, in an apparatus which uses a relativelylow-priced reference clock such as a Home evolved Node B (HeNB) and arepeater, flexible and stable CA implement is possible.

An embodiment of the present disclosure enables controlling generationof a reference clock based on a CC which has the best channel qualityamong CCs thereby stably controlling a clock.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. An apparatus for supporting carrier aggregation,the apparatus comprising: a plurality of component carrier (CC)circuits, each of the plurality of CC circuits configured to estimate afrequency offset for a related CC; a reference clock generatorconfigured to generate a reference clock using at least one frequencyoffset of frequency offsets estimated by corresponding two or more ofthe plurality of CC circuits; and a plurality of phase lock loop (PLL)circuits, each of the plurality of PLL circuits configured to generate areception carrier frequency or a transmission carrier frequency for atleast one related CC corresponding to the at least one frequency offsetused in the generating of the reference clock.
 2. The apparatus of claim1, wherein the plurality of PLL circuits comprises a set of receptionPLL circuits configured to generate the reception carrier frequency, anda set of transmission PLL circuits configured to generate thetransmission carrier frequency.
 3. The apparatus of claim 1, furthercomprising: a controller configured to select the at least one frequencyoffset from the frequency offsets as at least part of a referencefrequency offset.
 4. The apparatus of claim 1, further comprising: acontroller configured to compensate the estimated frequency offset usingat least one of the plurality of CC circuits.
 5. The apparatus of claim4, wherein the controller is further configured to: refrain fromcompensating the estimated frequency offset based at least in part on adetermination that the at least one frequency offset is selected as atleast part of a reference frequency offset.
 6. The apparatus of claim 1,wherein the plurality of PLL circuits are further configured to:compensate the estimated frequency offset corresponding to the at leastone related CC.
 7. The apparatus of claim 1, further comprising: acontroller configured to select the at least one frequency offset basedat least in part on channel quality information corresponding to atleast one of the plurality of CC circuits.
 8. The apparatus of claim 7,wherein the channel quality information comprises acarrier-to-interference and noise ratio, reference signal receivedpower, reference signal received quality, a reference signal strengthindicator, a channel quality indicator, a block error rate, or anycombination thereof.
 9. The apparatus of claim 1, wherein the referenceclock generator comprises a temperature compensated crystal oscillator,a voltage controlled-TCXO, or a digitally compensated crystaloscillator.
 10. The apparatus of claim 1, wherein each of the pluralityof CC circuits comprises: a plurality of frequency down converters, eachof the frequency down converters configured to down-convert a referencereception carrier frequency received from a first corresponding PLLcircuit of the plurality of PLL circuits, the first corresponding PLLcircuit including a reception PLL circuit; a plurality of frequency upconverters, each of the frequency up converters configured to up-converta reference transmission carrier frequency received from a secondcorresponding PLL circuit of the plurality of PLL circuits, the secondcorresponding PLL circuit including a transmission PLL circuit; afrequency offset estimator configured to estimate the at least onefrequency offset using a difference between the reference receptioncarrier frequency and the reception carrier frequency; a receptionfrequency offset compensator (RFOC) configured to compensate a receptionfrequency offset converted by corresponding one of the plurality offrequency down converters using the estimated frequency offset; and atransmission frequency offset compensator (TFOC) configured tocompensate a transmission frequency offset converted by correspondingone of the plurality of frequency up converters using the estimatedfrequency offset.
 11. The apparatus of claim 10, wherein the RFOC or theTFOC comprises a phase rotator, a read-only memory table, a complexmultiplier based-phase converter, or any combination thereof.
 12. Theapparatus of claim 11, wherein the phase rotator comprises a coordinaterotation digital computer.
 13. An apparatus for supporting carrieraggregation, the apparatus comprising: a first component carrier (CC)circuit configured to estimate a first frequency offset for a first CCto be processed by the first CC circuit; a second CC circuit configuredto estimate a second frequency offset for a second CC to be processed bythe second CC circuit; a reference clock generator configured togenerate a reference clock using the first frequency offset or thesecond frequency offset; and a phase lock loop (PLL) circuit configuredto generate a reception carrier frequency or a transmission carrierfrequency for the first CC or the second CC.
 14. The apparatus of claim13, wherein the PLL circuit comprises a set of one or more reception PLLcircuits configured to generate the reception carrier frequency, and aset of one or more transmission PLL circuits configured to generate thetransmission carrier frequency.
 15. The apparatus of claim 13, furthercomprising: a controller configured to select the first frequency offsetor the second frequency offset as at least part of a reference frequencyoffset.
 16. The apparatus of claim 13, further comprising: a controllerconfigured to compensate the estimated first frequency offset or theestimated second frequency offset using a corresponding one of the firstCC circuit and the second CC circuit.
 17. The apparatus of claim 13,wherein the PLL circuit is further configured to: compensate theestimated first frequency offset or the estimated second frequencyoffset related to a corresponding one of the first CC and the second CC.18. The apparatus of claim 13, further comprising: a controllerconfigured to select the first frequency offset or the second frequencyoffset based at least in part on channel quality informationcorresponding to at least one of the first CC circuit and the second CCcircuit.
 19. An apparatus for supporting carrier aggregation, theapparatus comprising: a first component carrier (CC) circuit configuredto: estimate a first frequency offset for a first CC to be processed bythe first CC circuit, and compensate the estimated first frequencyoffset; a second CC circuit configured to: estimate a second frequencyoffset for a second CC to be processed by the second CC circuit, andcompensate the estimated second frequency offset; a reference clockgenerator configured to generate a reference clock using the firstfrequency offset or the second frequency offset; and a phase lock loop(PLL) circuit configured to generate a reception carrier frequency or atransmission carrier frequency for the first CC or the second CC. 20.The apparatus of claim 19, wherein the PLL circuit comprises a set ofone or more reception PLL circuits configured to generate the receptioncarrier frequency, and a set of one or more transmission PLL circuitsconfigured to generate the transmission carrier frequency.
 21. Anapparatus for performing carrier aggregation, the apparatus comprising:a plurality of phase lock loop (PLL) circuits configured to:respectively generate a plurality of first carrier frequencies thatrespectively correspond to a plurality of component carriers (CCs) basedon a reference clock, and receive a plurality of second carrierfrequencies that respectively correspond to the plurality of CCs; and areference clock generator configured to generate a reference clock basedon comparing at least one of the plurality of first carrier frequenciesand corresponding at least one of the plurality of second carrierfrequencies.
 22. The apparatus of claim 21, wherein the apparatus is ahome evolved node B (HeNB), or a repeater.
 23. The apparatus of claim21, wherein the plurality of PLL circuits comprises: a set of receptionPLL circuits configured to generate the plurality of first carrierfrequencies; and a set of transmission PLL circuits configured togenerate a plurality of third carrier frequencies for transmittingsignals, the third carrier frequencies respectively corresponding to theplurality of CCs.
 24. A method for performing carrier aggregation, themethod comprising: generating a plurality of first carrier frequenciesrespectively corresponding to a plurality of component carriers (CCs)based on a reference clock; receiving a plurality of second carrierfrequencies respectively corresponding to the plurality of CCs;comparing at least one of the plurality of first carrier frequencieswith corresponding at least one of the plurality of second carrierfrequencies; and generating a reference clock based on the comparing.25. The method of claim 24, further comprising: compensating for atleast one frequency difference that results from the comparison andrespectively corresponds to at least one of the plurality of CCs. 26.The method of claim 25, further comprising: identifying a referencefrequency difference among the at least one frequency difference. 27.The method of claim 26, wherein the reference frequency difference isidentified based on information for channel quality corresponding toeach of the plurality of CCs.
 28. The method of claim 27, wherein eachinformation for channel quality comprises at least one of acarrier-to-interference and noise ratio, reference signal receivedpower, reference signal received quality, a reference signal strengthindicator, a channel quality indicator, or a block error rate.
 29. Anapparatus for performing carrier aggregation, the apparatus comprising:a plurality of antennas; and at least one processor configured to:generate a plurality of first carrier frequencies respectivelycorresponding to a plurality of component carriers (CCs) based on areference clock, receive, via the plurality of antennas, a plurality ofsecond carrier frequencies respectively corresponding to the pluralityof CCs, perform a comparison of at least one of the plurality of firstcarrier frequencies with corresponding at least one of the plurality ofsecond carrier frequencies, and generate a reference clock based on thecomparison.
 30. The apparatus of claim 29, wherein the at least oneprocessor is further configured to compensate for at least one frequencydifference that results from the comparison and respectively correspondsto the plurality of CCs.
 31. The apparatus of claim 29, wherein the atleast one processor is further configured to identify a referencefrequency difference among the at least one frequency difference. 32.The apparatus of claim 29, wherein the apparatus is a home evolved nodeB (HeNB), or a repeater.
 33. The apparatus of claim 29, wherein the atleast one processor comprises: a plurality of frequency down converters,each of the frequency down converters configured to down-convert thegenerated first carrier frequencies; a frequency offset estimatorconfigured to perform the comparison between the generated first carrierfrequencies and the received second carrier frequencies; and a frequencyoffset compensator configured to compensate for at least one frequencydifference that results from the comparison and respectively correspondsto at least one of the plurality of CCs.